Distinctive aspects of laboratory testing to evaluate mineral and bone metabolism in patients with chronic kidney disease

in Joint Bone Spine (2012), 79(suppl 2), 99-103

When should we measure vitamin D concentration in clinical pratice?

in Scandinavian Journal of Clinical and Laboratory Investigation. Supplementum (2012), 72(suppl 243), 129-135

The many recently published data on vitamin D have raised much interest in the medical community. One of the consequences has been a great increase in the prescription of vitamin D concentration ... [more ▼]

The many recently published data on vitamin D have raised much interest in the medical community. One of the consequences has been a great increase in the prescription of vitamin D concentration measurements in clinical practice. It must be reminded that only the measurement of 25-hydroxyvitamin D (25(OH)D) concentration is indicated to evaluate vitamin D status. Furthermore, since vitamin D insuffi ciency is so common, since treatment is inexpensive and has a large safety margin, and since we already have much data suggesting that besides its classic effects on bone and mineral metabolism, vitamin D may potentially be helpful for the prevention/management of several diseases, perhaps should it be prescribed to everyone without prior testing? In our opinion, there are however groups of patients in whom estimation of vitamin D status is legitimate and may be recommended. This includes patients in whom a “ reasonably ” evidence-based target concentration (i.e., based on randomized clinical trials when possible) should be achieved and/or maintained such as patients with rickets/osteomalacia, osteoporosis, chronic kidney disease and kidney transplant recipients, malabsorption, primary hyperparathyroidism, granulomatous disease, and those receiving treatments potentially inducing bone loss. Other patients in whom vitamin D concentration may be measured are those with symptoms compatible with a severe vitamin D defi ciency or excess persisting without explanation such as those with diffuse pain, or elderly individuals who fall, or those receiving treatments which modify vitamin D metabolism such as some anti-convulsants. Measurement of Vitamin D concentrations should also be part of any exploration of calcium/phosphorus metabolism which includes measurement of serum calcium, phosphate and PTH. [less ▲]

Interpretation of serum PTH concentrations with different kits in dialysis patients according to the KDIGO guidelines: importance of the reference (normal) values

in Nephrology Dialysis Transplantation (2012), 27

Background. The recommended target range for serum parathyroid hormone (PTH) in dialysis patients has changed from 150 to 300 pg/mL in the KDOQI guidelines to two to nine times the upper normal limit in ... [more ▼]

Background. The recommended target range for serum parathyroid hormone (PTH) in dialysis patients has changed from 150 to 300 pg/mL in the KDOQI guidelines to two to nine times the upper normal limit in the KDIGO ones. Although inclusion/exclusion criteria for the reference population are highly important, they are usually not mentioned in the commercial kits. In this study, we used the same reference population of vitamin D-replete normal subjects to establish reference values for 10 commercial PTH kits. We evaluated whether this may improve the classification of dialysis patients according to the KDIGO compared to the use of reference values proposed by the manufacturers. Methods. We measured serum PTH with 10 different kits in 149 haemodialysis patients, and 240 25-OH-vitamin D-replete (>75 nmol/L) individuals with an estimated glomerular filtration rate >60 mL/min/1.73 m2. Results. For the 10 kits, our upper normal limit was lower than those of the manufacturers. The difference was, however, variable from one kit to another. The two kits that yielded the lowest and the highest absolute concentrations classified differently 84/149 patients (56.4%) according to the KDOQI and 53/149 (36.2%) according to the KDIGO using the manufacturers’ normal value.Using our normal values significantly decreased the discrepancies with 24/149 patients (16.1%) being still classified differently. Taking the measurement uncertainty into consideration, 8% of the patients only remained differently classified by these two kits. Conclusions. Using the same vitamin-D-replete population to establish the reference range for 10 commercial PTH kits significantly improved the classification of haemodialysis patients according to the KDIGO target range. [less ▲]

Establishment of Parathyroid hormone reference range on 10 different assay kits: impact of the recruitment of the population

Poster (2011, September 18)

Validation of the Abbott Architect 25(OH)-vitamin D assay

in Clinical Chemistry & Laboratory Medicine (2011), 49(s1), 418

Dosage de la 25-OH vitamine D: attention aux erreurs analytiques!

in 27ème Congrès de la Société Française d'Endocrinologie - Deauville, 29 septembre - 2 octobre 2010 (2010, September)

Measurement uncertainty of 25-OH vitamin D determination with different commercially available kits: impact on the clinical cut offs

in Osteoporosis International (2010), 21

Les cibles thérapeutiques pour la PTH dans les nouvelles recommandations du KDIGO: la fin d'un cauchemar?

in Néphrologie & Thérapeutique (2010)

Vitamin D: current status and perspectives.

in Clinical Chemistry & Laboratory Medicine (2009), 47(2), 120-127

Abstract The role of vitamin D in maintaining bone health has been known for decades. Recently, however, the discovery that many tissues expressed the vitamin D receptor and were able to transform the 25 ... [more ▼]

Abstract The role of vitamin D in maintaining bone health has been known for decades. Recently, however, the discovery that many tissues expressed the vitamin D receptor and were able to transform the 25-OH vitamin D into its most active metabolite, 1,25-(OH)(2) vitamin D, has led to a very promising future for this "old" molecule. Indeed, observational studies, and more and more interventional studies, are raising the importance of a significant vitamin D supplementation for not-only skeletal benefits. Among them, 25-OH vitamin D has been found to play an important role in prevention of cancers, auto-immune diseases, cardiovascular diseases, diabetes, and infections. Vitamin D deficiency, defined as serum 25-OH vitamin D levels <30 ng/mL, is very common in our population. The cost/benefit ratio and some recently published studies are clearly now in favor of a controlled and efficient vitamin D supplementation in these patients presenting a 25-OH vitamin D level <30 ng/mL. More attention should also be focused on pregnant and lactating women, as well as children and adolescents. Clin Chem Lab Med 2009;47. [less ▲]

Circulating Concentrations of 25-Hydroxyvitamin D after a Single Oral Dose of 100.000 IU of Vitamin D2 or Vitamin D3

in Journal of Bone and Mineral Research (2008, September), 23